High pressure balloon

ABSTRACT

Composite fiber reinforced balloons for medical devices are prepared by applying a web of fibers to the exterior of a preformed underlayer balloon, encasing the web with a matrix material to form an assembly, and inserting the assembly into a preformed outer layer balloon to form the composite balloon.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.15/354,436, filed on Nov. 17, 2016, which is a Continuation of U.S.patent application Ser. No. 14/843,564, filed on Sep. 2, 2015, issued asU.S. Pat. No. 9,526,873, on Dec. 27, 2016, which is a Continuation ofU.S. patent application Ser. No. 14/494,894, filed on Sep. 24, 2014,issued as U.S. Pat. No. 9,144,666, on Sep. 29, 2015, which is aContinuation of U.S. patent application Ser. No. 13/735,111, filed onJan. 7, 2013, issued as U.S. Pat. No. 8,697,212, on Apr. 15, 2014, whichis a Divisional of U.S. patent application Ser. No. 13/247,628, filed onSep. 28, 2011, issued as U.S. Pat. No. 8,349,237, on Jan. 8, 2013, whichis a Continuation of U.S. application Ser. No. 11/407,576, filed on Apr.20, 2006, issued as U.S. Pat. No. 8,858,855, on Oct. 14, 2014 thecontents of which are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

Medical devices comprising catheter shafts and catheter balloons areused in an increasingly widening variety of applications includingvascular dilatation, stent delivery, drug delivery, delivery andoperation of sensors and surgical devices such as blades, and the like.The desired physical property profile for the balloons used in thesedevices varies according to the specific application, but for manyapplications a high strength robust balloon is necessary and goodsoftness and trackability properties are highly desirable.

Commercial high strength balloons having wall strengths in excess of20,000 psi have been formed of a wide variety of polymeric materials,including PET, nylons, polyurethanes and various block copolymerthermoplastic elastomers. A particular application which has a very highpressure requirement is reopening of stenoses which develop at or inlong-term shunt, ports or grafts employed for repeated blood access, forinstance with dialysis patients. Such stenoses are often highlycalcified and essentially must be subjected to very high pressure forsuccessful treatment. Moreover, frequently the vessels into which theaccess devices are connected are quite large. Consequently there is aneed for balloons whose pressure profile allows for use of pressures inexcess of 20 atm at balloon diameters which can exceed 5 mm.

Documents relating to fiber reinforced medical balloons include U.S.Pat. No. 4,896,669, Behate; U.S. Pat. No. 4,706,670, Andersen; U.S. Pat.No. 5,647,848, Jorgensen; U.S. Pat. No. 5,201,706, and U.S. Pat. No.5,330,429, Noguchi; U.S. Pat. No. 5,827,289, Reiley; and U.S. Pat. No.6,156,254, Andrews.

The art referred to and/or described above is not intended to constitutean admission that any patent, publication or other information referredto herein is “prior art” with respect to this invention. In addition,this section should not be construed to mean that a search has been madeor that no other pertinent information as defined in 37 C.F.R. § 1.56(a)exists.

Without limiting the scope of the invention a brief summary of some ofthe claimed embodiments of the invention is set forth below. Additionaldetails of the summarized embodiments of the invention and/or additionalembodiments of the invention may be found in the Detailed Description ofthe Invention below.

SUMMARY OF THE INVENTION

The invention pertains to fiber reinforced laminate composite balloonsand processes for preparing laminate composite balloons. Other aspectsof the invention pertain more generally to composite fiber reinforcedmedical device balloons.

In one inventive aspect, the balloon comprises an underlying balloonlayer, a fiber web disposed over the underlying balloon layer and amatrix material encasing the web.

In one inventive aspect, the balloon comprises an underlying balloonlayer, a fiber web disposed over the underlying balloon layer, a matrixmaterial encasing the web and an overlying balloon layer of radiallyoriented polymer material disposed over the fiber web and matrixmaterial.

In some aspects the invention pertains to manufacturing processes forpreparing composite fiber reinforced balloons. One such aspect of themethod comprises:

-   -   providing a preformed underlayer balloon;    -   applying a web of fibers to the exterior of said underlayer        balloon;    -   encasing the web with a matrix material to form an assembly of        underlayer balloon and fiber matrix;    -   providing a preformed overlayer balloon;    -   inserting the assembly of underlayer balloon and fiber matrix        into the preformed overlayer balloon form and    -   bonding said assembly and overlayer balloon to form said        composite fiber reinforced balloon.

In some embodiments, the invention pertains to balloons andmanufacturing methods as described above wherein the balloon has a fibermatrix ratio, taken as the thickness of the intermediate fiber andmatrix material to the total thickness of the balloon, in the range ofabout 0.51 to about 0.73.

These and other embodiments which characterize the invention are pointedout with particularity in the claims annexed hereto and forming a parthereof. However, for further understanding of the invention, itsadvantages and objectives obtained by its use, reference should be madeto the drawings which form a further part hereof and the accompanyingdescriptive matter, in which there is illustrated and described anembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side view of an underlayer balloon with a partialcutaway.

FIG. 2 is an enlarged cutaway view taken at line 2 of FIG. 1.

FIGS. 3 and 4 are views as in FIG. 2 illustrating steps of an embodimentof the inventive method.

FIG. 5 is a cutaway view taken at line 5 of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

All US patents and applications and all other published documentsmentioned anywhere in this application are incorporated herein byreference in their entirety.

While this invention may be embodied in many different forms, there aredescribed in detail herein specific embodiments of the invention. Thisdescription is an exemplification of the principles of the invention andis not intended to limit the invention to the particular embodimentsillustrated.

For the purposes of this disclosure, like reference numerals in thefigures shall refer to like features unless otherwise indicated.

Balloons of the invention are particularly suited to use in medicaldevices, for instance on balloon angioplasty catheters, in stentdelivery systems, perfusion balloon devices, cutting balloon devices,cryoplasty devices, and the like. Typically they will be mounted on acatheter or probe device.

Referring to the drawing FIGS. 1-5, several aspects of the inventiveprocesses are illustrated.

FIGS. 1 and 2 show an underlayer balloon 100 comprising waist regions102, 104, cone regions 106, 108 and body region 110. The underlayerballoon 100 can be in one embodiment formed of a single layer 122 of aradially oriented thermoplastic polymer.

FIG. 3 is a view as in FIG. 2, after application of a fiber web 126 andmatrix material 128. The fiber web 126 is encased by the matrix material128.

FIG. 4 is a view as in FIG. 3, after the application of an outerlayerballoon 140 to complete the composite balloon 200. The matrix material28 and fiber web 126 are sandwiched between the layer 122 provided bythe underlayer balloon and the layer 140 provided by the outerlayerballoon.

FIG. 5 is an isolated portion of the composite balloon wall 142 of theembodiment shown in FIG. 4.

Underlayer Balloon

In some aspects the invention pertains to a composite balloon, or methodof forming same, in which a web material is formed from fibers byapplication over an underlayer balloon form that becomes part of thecomposite balloon.

The underlayer balloon may be preformed in a manner known for formingmedical device balloons. For instance, a tubular parison of asemi-crystalline polymeric material may be radially expanded, orradially expanded with longitudinal stretching to form the underlayerballoon. Optionally the underlayer balloon may be still furtherprocessed before it is incorporated into the composite balloon. Theextruded parison used to prepare the underlayer balloon may be radiallyexpanded into a mold or by free-blowing. Alternatively, the parison maybe pre-stretched longitudinally before expansion or reformed in variousways to reduce thickness of the balloon cone and waist regions prior toradial expansion. The blowing process may utilize pressurization undertension, followed by rapid dipping into a heated fluid; a sequentialdipping with differing pressurization; a pulsed pressurization withcompressible or incompressible fluid, after the material has beenheated. Heating may also be accomplished by heating the pressurizationfluid injected into the parison. Examples of these techniques may befound in the patent documents mentioned elsewhere in this application orin U.S. Pat. No. 4,963,313, U.S. Pat. No. 5,306,246, U.S. Pat. No.4,935,190, U.S. Pat. No. 5,714,110 and U.S. Pat. No. 5,304,340. Variousknown methods of altering the properties of a radially expanded balloonsuch as heat-setting, heat shrinking, and/or radiation crosslinking mayalso be employed in forming the underlayer balloon. See U.S. Pat. No.5,403,340; EP 540858; and WO 98/03218.

The underlayer balloon may be formed of any material which may be madeby radial expansion of a tubular parison, typically thermoplasticpolymers. Documents pertinent to materials which may be employed thisway include U.S. Pat. No. 4,906,244, Pinchuk et al, and U.S. Pat. No.5,328,468, Kaneko, which describe polyamide balloons; U.S. Pat. No.4,950,239, Gahara, and U.S. Pat. No. 5,500,180, Anderson et al, whichdescribe balloons made from polyurethane block copolymers; U.S. Pat. No.5,556,383, Wang et al, and U.S. Pat. No. 6,146,356, Wang et al, whichdescribe balloons made from polyether-block-amide copolymers andpolyester-block-ether copolymers; U.S. Pat. No. 6,270,522, Simhambhatla,et al, which describes balloons made from polyester-block-ethercopolymers of high flexural modulus; U.S. Pat. No. 5,344,400, Kaneko,which describes balloons made from polyarylene sulfide; and U.S. Pat.No. 5,833,657, Reinhart et al, which describes balloons having a layerof polyetheretherketone. U.S. Pat. No. 5,250,069, Nobuyoshi et al, U.S.Pat. No. 5,797,877, Hamilton et al, and U.S. Pat. No. 5,270,086, Hamlin,describe still further materials which may be used to make suchballoons.

Such materials may include low, linear low, medium and high densitypolyethylenes; polypropylenes; poly(ethylene vinyl acetate) (EVA);poly(ethylene vinyl alcohol) (EVOH) and EVA/EVOH terpolymers;polyolefin-ionomers; ethylene-butylene-styrene block copolymers blendedwith low molecular weight polystyrene and, optionally, polypropylene,and similar compositions substituting butadiene or isoprene in place ofthe ethylene and butylene; poly(vinyl chloride); polyurethanes;polyesters and copolyesters; polycarbonate; thermoplastic elastomers;silicone-polycarbonate copolymers; polyamides; thermoplastic polyimides;liquid crystal polymers; ABS (acrylonitrile butadiene styrene); ANS(acrylonitrile styrene); Delrin polyacetal; PEI (polyetherimide);polyetheretherketone (PEEK) and PES (polyether sulfone). Physical blendsand copolymers of such materials may also be used.

Orientable polymers are among the preferred materials for forming theunderlayer balloon. Suitable orientable polymers include aromaticpolyesters, especially polyethylene terephthalate (PET). PET polymersmay have an initial intrinsic viscosity about 0.5 or more, for instance,0.6-1.3. Other high strength polyester materials, such as poly(ethylenenaphthalate) (PEN); and poly(butylene terephthalate) may also be used.Polyester copolymers incorporating ethylene terephthalate, ethylenenaphthalate, butylene terephthalate and/or butylene naphthalate repeatunits, may also be employed. Polyester copolymers such as the randomcopolymer made from dimethyl terephthalate dimethyl isophthalate andethylene glycol described in U.S. Pat. No. 5,330,428 Wang, et al. mayalso be employed.

Examples of polyamides which may be used include nylon 6, nylon 64,nylon 66, nylon 610, nylon 610, nylon 612, nylon 46, nylon 9, nylon 10,nylon 11, nylon 12, and mixtures thereof.

The underlayer balloon may be formed of polyurethanes such as Tecothane®from Thermedics. Tecothane® is a thermoplastic, aromatic, polyetherpolyurethane synthesized from methylene diisocyanate (MDI),polytetramethylene ether glycol (PTMEG) and 1,4-butanediol chainextender. Tecothane® 1065D and 1075D are examples. Other polyurethanesthat can be used include Isoplast® 301, a high strength engineeringthermoplastic polyurethane, and Pellethane® 2363-75D, both sold by DowChemical Co. References illustrating polyurethane balloon materialsinclude U.S. Pat. No. 4,950,239, to Gahara, U.S. Pat. No. 5,500,180 toAnderson et al, U.S. Pat. No. 6,146,356 to Wang, et al., and U.S. Pat.No. 6,572,813, to Zhang, et al.

Underlayer balloons may be also made of polyamide/polyether blockcopolymers. The polyamide/polyether block copolymers are commonlyidentified by the acronym PEBA (polyether block amide). The polyamideand polyether segments of these block copolymers may be linked throughamide linkages, however, most preferred are ester linked segmentedpolymers, i.e. polyamide/polyether polyesters. Suchpolyamide/polyether/polyester block copolymers are made by a moltenstate polycondensation reaction of a dicarboxylic polyamide and apolyether diol. The result is a short chain polyester made up of blocksof polyamide and polyether.

Polyamide/polyether polyesters are sold commercially under the Pebax®trademark. Examples of suitable commercially available polymers are thePebax® 33 series polymers with hardness 60 and above, Shore D scale,especially Pebax® 6333, 7033 and 7233. These polymers are made up ofnylon 12 segments and poly(tetramethylene ether) segments linked byester groups.

It is also possible to utilize polyester/polyether segmented blockcopolymers. Such polymers are made up of at least two polyester segmentsand at least two polyether segments. The polyether segments are the sameas previously described for the polyamide/polyether block copolymersuseful in the invention. The polyester segments are polyesters of anaromatic dicarboxylic acid and a two to four carbon diol.

The polyether segments of the polyester/polyether segmented blockcopolymers are aliphatic polyethers having at least 2 and no more than10 linear saturated aliphatic carbon atoms between ether linkages. Morepreferably the ether segments have 4-6 carbons between ether linkages,and most preferably they are poly(tetramethylene ether) segments.Examples of other polyethers which may be employed in place of thepreferred tetramethylene ether segments include polyethylene glycol,polypropylene glycol, poly(pentamethylene ether) and poly(hexamethyleneether). The hydrocarbon portions of the polyether may be optionallybranched. An example is the polyether of 2-ethylhexane diol. Generallysuch branches will contain no more than two carbon atoms. The molecularweight of the polyether segments is suitably between about 150 and2,500, preferably between 250 and 1000.

The polyester segments of the polyester/polyether segmented blockcopolymers are polyesters of an aromatic dicarboxylic acid and a two tofour carbon diol. Suitable dicarboxylic acids used to prepare thepolyester segments of the polyester/polyether block copolymers areortho-, meta- or para-phthalic acid, naphthalenedicarboxylic acid ormeta-terphenyl-4,4′-dicarboxylic acids. Preferred polyester/polyetherblock copolymers are poly(butyleneterephthalate)-block-poly(tetramethylene oxide) polymers such asArnitel® EM 740, sold by DSM Engineering Plastics, and Hytrel® polymers,sold by DuPont, such as Hytrel® 8230.

A suitable thermoplastic polyimide is described in U.S. Pat. No.5,096,848 and is available commercially under the tradename Aurum® fromMitsui Toatsu Chemicals, Inc., of Tokyo, Japan.

Examples of liquid crystal polymers include the products Vectra® fromHoechst Celanese; Rodrun® from Unitika; LX and HX series polymers andZenite™ polymers from DuPont; Sumikosuper™ and Ekonol™ from SumitomoChemical; Granlar™ from Grandmont; and Xydar® from Amoco. Suitably theliquid crystal polymer materials when employed in the underlayer balloonare blended with another thermoplastic polymer such as PET, nylon 12, ora block copolymer such as Pebax® 7033 or 7233 or Arintel® EM 740 orHytrel 8230. The liquid crystal polymer may be present as filaments in amatrix of the blend polymer.

Alternatively, the underlayer balloon may be obtained by polymerizationof a curable composition on a mold form, for instance as described incommonly owned applications US 2005-0015046 A1, and/or US 2006-0008606A1.

The underlayer balloon is formed at a thickness which will provide asufficiently rigid profile upon inflation to a low pressure, for example2-3 atm, to permit direct application of fibers thereto in a mannerwhich forms a fiber web overlying the balloon. Preferably the underlayerballoon is substantially radially oriented or biaxially (radially andlongitudinally) oriented. The underlayer balloon may have a wallthickness, single wall basis, of from about 5 μm to about 50 μm(0.0002-0.002 inches), for instance 8 to 30 μm (0.0003-0.0012 inches),suitably about 10 to about 25 μm (0.0004-0.0010 inches).

Fiber Web

Various techniques for forming webs are known. Suitable webs may bebraids, weaves, mesh, helical windings, knits or random rovings. The webmay be formed of different materials, for instance if anisotropiclongitudinal lengthening and diameter expansion properties are desired.

The fiber selection and the web pattern can influence the distensionproperties of the composite balloon. Fiber tension during application tothe underlayer balloon can also affect distension of the compositeballoon, especially if elastomeric fibers are employed in whole or inpart. In some preferred embodiments, however, the composite balloon issubstantially non-distensible in both the longitudinal and radialdirections, in which case the fibers have very low elongation, and thepattern is selected to provide minimal expansion. Weaves or braids areparticularly desirable web-forms in these embodiments. A circularbraider may be employed to apply the fibers to the underlayer balloon.

The web pattern may provide crossing fibers at any angle. Typically atleast one set of the fibers will wind helically around the circumferenceof the underlayer balloon. In at least some embodiments a set oflongitudinal fibers is provided, running parallel to the longitudinalaxis over at least a portion of the underlayer balloon. The longitudinalfibers may be inelastic. In some embodiments the longitudinal fibers areinterwoven or braided into the web pattern with fibers that windhelically around the balloon, for instance, the helical fibers may crossover and under the longitudinal fibers in an individually or groupedalternating fashion to provide the weave or braid. Crossing fibers thatrun at several different angles may be used. For instance, longitudinalfibers may be crossed both by fibers running at 45° and at 135° thereto.In some embodiments, the braiding angle may be 68 to 70. Particularlywith fiber webs produced using mechanical braiders, crossing angles thatproduce optimal reinforcement may not occur with optimal gap spacingbetween fiber crossings. Groupings of individual fibers may be employedto reduce gap spacing at any desired crossing angle. For instance,crossing groupings of 2-6 fibers by 2-6 fibers may give better resultsthan 1×1 crossings. The groupings may have different sizes, for instance2 (longitudinal) by 4 (45° helical) by 4 (135° helical).

The fibers may be monofilament or multifilament fibers. Any size whichis suitable may be used. For example, in some embodiments, the fibersmay range in size from 1 to 50 μm or in denier from 10-100. In someembodiments, the denier is from 25-50. Moreover, deviations from thissize range can be achieved in some cases without departing from theinvention.

Individual filaments in a multifilament fiber may have denier size lessthan 10, for instance from 1-5 denier. Larger filaments may also beemployed in multifilament fibers. Multifilament fibers may be a blend offibers of different materials.

The fiber material may be polyester, polyolefin, polyamide,polyurethane, liquid crystal polymer, polyimide, carbon, glass, mineralfiber or a combination thereof. Polyesters includepolyethyleneterephthalate (PET), polybutylene terephthalate (PBT), andpolytrimethylene terephthalate (PTT). Polyamides include nylons andaramids such as Kevlar®. Liquid crystal polymers include Vectran®.Polyolefins include ultrahigh molecular weight polyethylene, such asDyneema,® sold by DSM Dyneema BVm Heerlen, Netherlands, Spectra® fibers,sold by Honeywell, and very high density polyethylene, and polypropylenefibers. Elastomeric fibers can be used in some cases. In some specificembodiments of the invention, the fibers are high strength materialswhich have a very low elongation and creep, such as aramid, liquidcrystal polymer, or ultrahigh molecular weight polyethylene described inU.S. Pat. No. 5,578,374, U.S. Pat. No. 5,958,582 and/or U.S. Pat. No.6,723,267. Fibers comprising carbon nanotubes or carbon nano-fibers maybe suitable. Other carbon materials may also be suitable in someapplications.

In some embodiments the fiber web may comprise multiple layers offibers. However in other embodiments the fiber web has regions betweencrossings where a single fiber strand is employed to minimize theballoon profile. The strands may be manipulated to flatten as they areapplied to increase the area covered by a single strand and minimize theprofile of the fiber and of the overall balloon.

Friction Enhancement

To facilitate integrity of the web applied to the cone portion of theunderlayer balloon, a friction-enhancing material may be provided at theinterface between the underlayer balloon and the web, at least over thecone portion. The web fibers may be coated with a friction-enhancingmaterial, or a layer of friction-enhancing material may be applied to atleast the cone portion of the underlayer balloon before application ofthe web fibers, or both. The friction enhancing material may also beprovided at the interface between the underlayer balloon and the webover other portions of the balloon, for instance over the waist and/orbody portions.

The friction-enhancing material may be a polymer that has a highercoefficient of friction than either or the underlayer balloon and thefiber and which is high enough that the fibers do not substantially slipoff or around on the cone during web formation. Coefficient of frictionis suitably determined per ASTM D3702 against a polished steel surfaceand values of about 0.7 or higher are recommended, especially about 0.8and higher. Exemplary materials may be rubbery elastomeric thermoplasticpolymers, for instance, styrene-olefin block copolymers andacrylonitrile block copolymers. In some cases urethane-basedthermoplastic elastomers, ester-based thermoplastic elastomers,olefin-based thermoplastic elastomers, and amide-based thermoplasticelastomers may be suitable. Linear low density polyethylene, very lowdensity polyethylene, polyethylene-α-olefin copolymers orpolycarbonate-urethane copolymers may be suitable in some cases.

One group of friction enhancers includes styrene-olefin thermoplasticelastomers. The styrene-olefin thermoplastic elastomer is a blockcopolymer having a soft segment and a hard segment within a molecule.The soft segment is a unit that is obtained from polymerization of anolefin, e.g., a polyisobutylene block, a polybutadiene block or apolyisoprene block. The component constituting the hard segment is aunit of styrene block, for example, that is obtained from a compoundhaving one or at least two types selected from styrene and itsderivatives, e.g., α.-methyl styrene, vinyl toluene, p-tertiary butylstyrene, 1,1-diphenyl ethylene and others.

Specific examples of the styrene-olefin thermoplastic elastomersinclude: styrene-isobutylene-styrene block copolymer (SIBS);styrene-butadiene-styrene block copolymer (SBS);styrene-ethylene-butylene-styrene block copolymer (SEBS);styrene-isoprene-styrene block copolymer (SIS);styrene-ethylene-propylene-styrene block copolymer (SEPS);styrene-ethylene-ethylene-propylene-styrene block copolymer (SEEPSstructure); and modified block copolymers thereof. The content ofstyrene (or its derivatives) in each of the SIBS, SBS, SEBS, SIS, SEPSand SEEPS structures is preferably in a range of 10-50 wt. %, and morepreferably in a range of 15-45 wt. % within the copolymer. A particularexample is SIBS with about 17 wt % styrene.

A friction-enhancing coating material may also be an adhesive. Forinstance, the adhesive may be one that provides at least some tackduring application of the fibers. The adhesive may be a pressuresensitive, hot melt, solution, dispersion or curable material. In someembodiments of the invention, the adhesive will set up further afterapplication of the fiber to provide an adhering bond between the fibersand the balloon which is stronger than the initial tack adhesion.Partially cured radiation curable acrylate coating materials areexemplary.

The friction-enhancing coating may be applied from a solution ordispersion. In the case of a hot melt or curable adhesive, the coatingmay be applied neat. Suitable coating thicknesses are from about 1 toabout 25 μm, for instance from about 2 μm to about 20 μm or from about 5to about 10 μm.

Matrix

A polymeric matrix material is applied over the web and over any exposedportions of the underlayer balloon. The matrix material should bind tothe material that is at least partially exposed to the matrix materialunder the particular technique employed. The exposed material may be oneor more of the web fiber material, the underlayer balloon and, ifemployed, the friction enhancing material. The matrix material may bethe same or similar to the friction-enhancing material. The matrixmaterial may also be the same or similar to the bulk material of theunderlayer balloon, or it may be a wholly different material from boththe friction-enhancing material and the underlayer balloon material. Thematrix material in some embodiments is heat activatable, i.e. afterapplication adhesive properties can be activated by heating.

The matrix material may be applied from solvent or dispersion. In somecases a curable liquid which sets up after application may be employedas matrix material. The matrix material may also be applied from themelt, for instance by spraying or extruding over the web.

Examples of matrix materials which may be employed include thestyrene-olefin thermoplastic elastomers already described.Polyurethanes, for instance silicone modified polyurethanes may beemployed. UV curable compositions as described in more detail in US2006-0008606 A1 may also be employed.

A solution or dispersion or a polymer formulation having hot-meltadhesive properties, i.e. one that after drying may still be activatedwith heat to bond to a subsequently applied substrate, may be used.

In some embodiments the matrix material and the friction-enhancingmaterial, in combination, also bind the filaments of the fibrousmaterial to the underlayer balloon.

Outerlayer Balloon

An outerlayer balloon is positioned over the assembly of underlayerballoon, fiber web and matrix material to form a composite balloon.

The outerlayer balloon is a thin molded balloon and may be preformed ina manner known for forming medical device balloons, for instance by anyof the means described herein for forming the underlayer balloon. Thematerials of the outer layer balloon may be selected from the samematerials already identified for the underlayer balloon. The material ofthe outer layer balloon may be the same or different from that of theunderlayer balloon.

The outerlayer balloon is formed with an inner diameter which willreceive the underlayer balloon and web matrix combination. In someembodiments, the outerlayer balloon is radially oriented or biaxially(radially and longitudinally) oriented.

The outer layer balloon may have any suitable wall thickness. In someembodiments, the wall thickness may be comparable to that of theunderlayer balloon, for example, on single wall basis from about 5 μm toabout 50 μm (0.0002-0.002 inches), for instance from about 8 to about 30μm (0.0004-0.0012 inches), suitably from about 10 to about 25 μm(0.0004-0.0010 inches).

Forming the Composite Balloon

The combination of the above described layers, as mentioned above, formsa composite balloon that is flexible and has high strength and a highburst pressure. In forming the composite balloon, the underlayer balloon122 can be formed and molded using a conventional molding process. Themolded underlayer balloon may then be inflated and both ends sealed. Theunderlayer balloon 122 optionally may then be coated with a frictionenhancing material 124, such as a pressure sensitive adhesive. The fiberweb 126 is then applied to the surface of the underlayer balloon 122,suitably as a braid of fibers of Spectra® or Vectran® materials, or thelike. The fiber web 126 is then encased with matrix material 128. As aparticular example a solution or dispersion or a polymer formulationhaving hot-melt adhesive properties upon drying may be used.

After any solvent is dried off, the pressure is released. The assemblyof the underlayer balloon 122, fiber web 126 and matrix 128 is theninserted into a previously formed outerlayer balloon 140. The outerlayerballoon 140 may be slightly larger than the underlayer balloon 122 or itmay have the same dimensions. The proximal and distal waist of theouterlayer balloon 140 may be larger than those of the underlayerballoon 122 to ease insertion.

After insertion, the combination balloon is inflated and heated at atemperature above the temperature at which the underlayer and outerlayer balloons were formed. For instance if the underlayer and outerlayer balloons are blown at a temperature in the range of about 90° C.to about 100° C., a heat temperature in the range of from about 110° toabout 130° may be employed, for instance about 115° C. A suitable heattime may be from about 15 seconds to about 5 minutes, for instance aboutone minute. The heated inflation pressure is suitably about the same orhigher pressure than the pressure at which the underlayer balloon or theouter layer balloon, whichever was higher, for example the range of40-50 psi. During heating the matrix material desirably is activated toadhere to the outerlayer balloon to laminate the layers together.

In some embodiments, the heat set temperature is set by the adhesiveactivation temperature instead of higher than the balloon moldingtemperature.

In general the conditions for formation of the underlayer and outerlayers may be substantially the same so that they will have similarbehavior during heating. However, in some cases it may be advantageousfor the underlayer and outer layer balloons to have been formed atdifferent temperature and or pressure conditions such that the outerlayer balloon shrinks slightly during heating while the underlayerballoon remains unchanged or expands slightly. Such technique mayincrease the bonding pressure of the outer layer balloon to the adhesivematrix material and assist in flattening fiber strands therebetween soto further minimize the total balloon thickness.

Although it should be understood that in some embodiments there is nocoating on the outerlayer balloon, the composite balloon may have acoating of a lubricous material or which comprises drug, as is generallyknown. See, for instance U.S. Pat. No. 5,135,516; U.S. Pat. No.5,026,607; U.S. Pat. No. 5,304,121; U.S. Pat. No. 5,576,072; U.S. Pat.No. 5,503,631; U.S. Pat. No. 5,509,899; U.S. Pat. No. 5,693,034; U.S.Pat. No. 6,110,483; U.S. Pat. No. 5,702,756; U.S. Pat. No. 6,528,150;and U.S. Pat. No. 6,673,053.

The composite balloon may have a single wall thickness of about 50 toabout 250 μm, suitably about 50 to about 230 μm. In some embodiments,the single wall thickness of about 50 to about 80 μm with a target at 60μm.

Wall strengths for such balloons may be in excess of about 15,000 psi(103,421 kPa), typically at least about 18,000 psi (124,106 kPa), and inmost cases in the range of about 25,000 to about 40,000 psi. Balloondiameters may range from about 1.5 to about 14 mm. The resultingcomposite balloons also exhibit repeat inflation durability andstrength. In testing, composite balloons of the present invention passed100 cycles at 20 ATM.

Fiber-Matrix/Balloon Thickness Ratio

In some aspects the invention relates to the particular ratio of fiberand matrix material employed relative to the overall balloon thickness.

Referring now to FIG. 5, the wall 142 of the composite balloon has anoverall thickness 144, referred to as the composite balloon wallthickness 144, and a thickness 146 of the combination of the fiber web126 and matrix material 128, referred to as the fiber matrix thickness146. In order to minimize the profile of the medical balloon, while atthe same time maintain a high burst pressure, the present invention alsocontemplates minimizing the thickness of the fiber strands used to formthe fiber web. To achieve this reduced fiber size, the yarn that makesup the fiber web 126 is desirably manipulated to spread out as it isapplied so as to cover a greater area.

To measure the effect of fiber spreading, a fiber matrix ratio (R) isestablished. The ratio (R) reflects the relative thickness of the fiberand matrix material layer, compared to the total balloon thickness at alocation where a single strand of fiber lies between the under and outerlayers. Referring again to FIG. 3, R is taken as the thickness 146divided by the composite balloon wall thickness 144.

The fiber matrix ratio may be suitably calculated based on 30 randommeasurements to determine total thickness. The fiber matrix iscalculated using a scanning electron microscope or some other suitabledevice. The sample thickness is measured over a 10 mm squared area.

The inventors of the present invention have found that the fiber matrixratio is an effective tool in optimizing the balance between minimizingprofile while maintaining high burst pressure for fiber reinforcedballoon. In some embodiments, fiber reinforced balloons having an Rvalue of between about 0.51 and about 0.73 have been found to exhibitfavorable characteristics.

The following examples illustrate the invention in preliminary,non-optimized trials.

Example

Underlayer balloons were prepared by radial expansion of extruded tubesof Pebax® 7233 polymer. The underlayer balloons had an average doublewall thickness in the body region of approximately 0.0016 inches, amolded diameter of approximately 8 mm and a molded body length ofapproximately 2 cm. The underlayer balloons were sterilized withethylene oxide according to a conventional protocol. At this stage,three balloons were retained, unbraided, as controls for comparisonpurposes.

The underlayer balloons were heat-sealed at their distal end. Theproximal end was connected to a pneumatic syringe and pressurizedballoon component to a firm stiffness (1-2 atm internal pressure).

A coating of pressure sensitive adhesive, HL-2081 from H.B. Fuller, wasapplied to the exterior surface of the underlayer balloon by handdipping the pressurized balloon component into a solution of 25%adhesive in Toluene, drawing the balloon component out of solution andallowing it to dry.

A braiding machine was utilized to weave a web of fibers of 50 denierfiber form Dyneema from DSM around the inflated balloon components.Speeds were adjusted as braiding progressed in a manner directed toachieve a single layer braiding with an estimated 68-70 degree braidingangle.

The pressurized balloon component was then dipped into a solution of 10%hot melt HM-0230 in toluene, drawing the balloon component out ofsolution and letting it thoroughly dry.

Overlayer balloons of Pebax® 7233 polymer were prepared in the samemanner and with the same dimensions as the underlayer balloons.

Resulting balloons made from the above process had a fiber matrix ratioof 0.73 and an average burst of 30 ATM.

The above disclosure is intended to be illustrative and not exhaustive.This description will suggest many variations and alternatives to one ofordinary skill in this art. The various elements shown in the individualfigures and described above may be combined or modified for combinationas desired. All these alternatives and variations are intended to beincluded within the scope of the claims where the term “comprising”means “including, but not limited to”.

Further, the particular features presented in the dependent claims canbe combined with each other in other manners within the scope of theinvention such that the invention should be recognized as alsospecifically directed to other embodiments having any other possiblecombination of the features of the dependent claims. For instance, forpurposes of claim publication, any dependent claim which follows shouldbe taken as alternatively written in a multiple dependent form from allprior claims which possess all antecedents referenced in such dependentclaim if such multiple dependent format is an accepted format within thejurisdiction (e.g. each claim depending directly from claim 1 should bealternatively taken as depending from all previous claims). Injurisdictions where multiple dependent claim formats are restricted, thefollowing dependent claims should each be also taken as alternativelywritten in each singly dependent claim format which creates a dependencyfrom a prior antecedent-possessing claim other than the specific claimlisted in such dependent claim below.

This completes the description of the invention. Those skilled in theart may recognize other equivalents to the specific embodiment describedherein which equivalents are intended to be encompassed by the claimsattached hereto.

1. An expandable medical balloon comprising: an underlying balloon layercomprising a thermoplastic elastomer, the underlying balloon layer isbiaxially oriented; a friction enhancing layer disposed on at least aportion of an outer surface of the underlying balloon layer; a fiber webdisposed on the underlying balloon layer and disposed on the frictionenhancing material; and an overlying balloon layer comprising athermoplastic elastomer.
 2. The expandable medical balloon of claim 1wherein the underlying balloon layer has a wall thickness of about 5microns to about 50 microns.
 3. The expandable medical balloon of claim1 wherein the underlying balloon layer has a thickness of about 10microns to about 25 microns.
 4. The expandable medical balloon of claim1 wherein the underlying balloon layer has a thickness of about 15microns.
 5. The expandable medical balloon of claim 1 wherein ratio ofthe thickness of the underlying balloon layer to overlying balloon layeris about 3:1 to about 5:1.
 6. The expandable medical balloon of claim 4wherein the ratio of the thickness of the underlying balloon layer tothe overlying balloon layer is about 3.5:1.
 7. The expandable medicalballoon of claim 1 wherein the underlying balloon layer has a shore Dhardness of about
 70. 8. The expandable medical balloon of claim 1wherein the expandable medical balloon has an actual burst strength ofabout 30 ATM.
 9. The expandable medical balloon of claim 1 wherein theexpandable medical balloon has a fiber web to friction enhancing layerand overlying balloon layer ratio (R) of between about 0.51 and about0.73.
 10. The expandable medical balloon of claim 1 wherein theunderlying balloon layer comprises polyether-block-amide.
 11. Anexpandable medical balloon comprising: an underlying balloon layercomprising a thermoplastic elastomer, the underlying balloon layer isbiaxially oriented; a friction enhancing layer disposed on at least aportion of an outer surface of the underlying balloon layer; a fiber webdisposed on the underlying balloon layer and on the friction enhancinglayer; and an overlying balloon layer comprising a thermoplasticelastomer; wherein a ratio of thickness of the underlying balloon layerto the overlying balloon layer is about 3:1 to about 5:1.
 12. Theexpandable medical balloon of claim 11 wherein the friction enhancinglayer comprises thermoplastic polyurethane.
 13. The expandable medicalballoon of claim 11 wherein the underlying balloon layer has a wallthickness of about 5 microns to about 50 microns.
 14. The expandablemedical balloon of claim 11 wherein the underlying balloon layer has athickness of about 10 microns to about 25 microns.
 15. The expandablemedical balloon of claim 11 wherein the underlying balloon layer has athickness of about 15 microns.
 17. The expandable medical balloon ofclaim 11 wherein the ratio of the thickness of the underlying balloonlayer to the overlying balloon layer is about 3.5:1.
 18. The expandablemedical balloon of claim 11 wherein the ratio of the thickness of theunderlying balloon layer to the friction enhancing layer is about 3:1 toabout 5:1.
 19. An expandable medical balloon comprising: an underlyingballoon layer comprising a polymer material, the underlying balloonlayer is biaxially oriented; a friction enhancing layer disposed on atleast a portion of an outer surface of the underlying balloon layer; afiber web disposed on the underlying balloon layer and disposed on thefriction enhancing layer; and an overlying balloon layer comprising athermoplastic elastomer.
 20. The expandable medical balloon of claim 19wherein the underlying balloon layer comprises polyether-block-amide,polyamide, or a combination thereof.